SupportAssist - installation failed message.

Sure, I won't do that !

If MSoft publish a new version of .NET runtime, there is surely good reason for that. Most likely, to avoid some security issue.

While I'm convinced there is no conflict between DSA and .Net 6.0.10 : For me, the most likely reason of the issue is that, at install, DSA checks if AT LEAST .Net 6.0.9 is installed. And when it founds that 6.0.10 version is installed, it compares this version number wit 6.0.9, but erroneously makes its comparision alphabetically instead of numerically (and, yes, alphabetically speaking, 6.0.10 is "before" 6.0.9). As a result, DSA considers that .NET has to be "upgraded" to 6.0.9 which is (hopefully !) impossible from .NET perspective.

So, rather than to ask users to do such things, please ask technical engineers to create a new version of DSA installer that, when it checks currently installed version of .NET, is able to understand that if minimum version is 6.0.9, this requirement is already fulfilled if 6.0.10 is already installed.

Or, in case there is really incompatibility of DSA with 6.0.10 (I don't believe it 1 second), fix DSA itself to resolve the conflict... or ask MSoft to publish a 6.0.11 that solve the issue.

But surely, I won't downgrade an "OS layer soft" (ie. .NET runtime) to "please" a "User layer" soft (ie. DSA)

I am really surprised that you even dare to make this request. It is not serious, and is not a sign of seriousness on the part of Dell

PS : I just checked in MSoft Catalog  : .NET 6.0.10 is indeed a security update (KB5019351 and not KB5015391 as mentioned by @lmacri )

Thank you very much Nathalia M for this solution which worked for me because I had received a message from support assist asking me to update it in vain after having tried several times I installed version 6 of net runtime and then I went to this link to reinstall Support Assist. I'm really happy support assist is working again.

instead of uninstalling etc [recommendation from DELL people] if you have a later .NET runtime you should be able to use that (not the archaic v5.0 that DDM may require). My earlier post said

DDM installed OK but at runtime then requires .NET v5.0 runtime, but failed to download that on system that lacks .NET v5.0 although box had the latest .NET v7.0
I found that editing C:\Program Files\Dell\Dell Display Manager 2.0\DDM.runtimeconfig.json happily used my latest version
{
"runtimeOptions": {
"tfm": "net7.0",
"framework": {
"name": "Microsoft.WindowsDesktop.App",
"version": "7.0.0"
}
}
}

Dell should be embarrassed that the "accepted solution" forces the user to uninstall the existing tool and install prerequisites to get it to work.  That's YOUR job.  Provide a freaking installer that actually works!  Anyway, your 1st step doesn't actually work for me -- running the MS Install Uninstall tool doesn't actually find any issues, yet I still can't install SupportAssist.  Should I attempt to install via Add/Remove programs?

UPDATE SOLUTION SOLVED!

If you have MS .NET Runtime version 6.0.11 then you are missing the HostFXR.dll file.
Go to https://www.dll-files.com/hostfxr.dll.html and download HostFXR.dll v3.0.19 (x64).
Now place the .dll file to C:\Program Files\dotnet\host\fxr\7.0.0 then restart Windows.

Or install Microsoft .NET Runtime & Microsoft .NET Desktop Runtime v7.0.0 (86/64).

I have a XPS 13 9360, I tried all of the above and had tech support remote into my system and still can't install support assist. Any update with a workable solution?

Hello guys, I was trying to get it running for two days and found what was a problem at least on my machine. I looked into Event Viewer if there is anything and was: 

Product: Dell SupportAssist -- Error 1317. An error occurred while attempting to create the directory C:\ProgramData\Dell\SupportAssist

Funny that logs were still written in this folder, but nothing else had permission somehow. I fixed it by adding Everyone full rights during installation to C:\ProgramData\Dell folder.
I hope this will help anyone

Dell: Consider bundling the .NET Runtime that you require along with the rest of its prerequisites with the application for next update. I'm surprised this is a problem when .NET 6 explicitly support self-contained executables. This is not supposed to be a problem.